If you made a mistake (for example, perhaps you posted one of your
articles multiple times by accident), you won't be able to cancel the
article from your news reader software as you normally might.

Instead, to have an article canceled, send us email at
news-answers-request@mit.edu with the Subject line "Urgent: cancel
needed".  Specify your article's Subject line, Newsgroups, Message-ID
(if convenient), and what went wrong such that you need the article
canceled.  (Note that this only applies to articles cross-posted to
*.answers.  We can't cancel other articles, but you should be able to
cancel any article you post to non-moderated newsgroups yourself.)  We
make every effort to process cancel requests as quickly as possible.